The best advice is of course not to play but if you have to I would suggest avoiding sharp tactical  play and go for something strategic or maybe just get the queens off. I can't guarantee that will enable you to win because you may be playing the type of game that isn't your strong point.

Coffee.
Maybe some chocolate biscuits too. Bourbons or chocolate digestives. Be careful when dunking though.

More and better exercise leads to better sleeping habits and better overall energy.  Healthy body = healthy mind and all that.  This applies to surviving travel, etc. as well.  Avoid caffeine.  Fruit and natural sugars are better...

Hello all.

Analyzing my results and the reasons for them, I have noticed that I am particularly prone to playing badly when tired, I suspect more so than most people. I take longer to spot tactics, longer to understand my opponents' plans (if I do at all), and have a harder time visualising concrete variations. All these small factors add up to the single biggest predictor of underperformance and rating loss in my game.

I know many trainers (e.g. Heisman) advise simply not playing when tired, but this is hard to implement in practice. Maybe I've travelled to a tournament and it would seem a bit ridiculous not to play after all, I'm committed to a team, or I simply struggle to fall asleep during a tournament. I always finish a tournament I've started as a matter of principle (withdrew once due to fever and nausea, after bravely trying, but losing two straight games). Oh, how I envy those people who can show up on sunday mornings after a night out and still play a reasonable game!

So given that, for whatever reasons, we will sometimes have to play games less than fully rested, is there something that can be done chess-wise to minimize the damage? 

Should we aim for long, theoretical lines in the hope of conserving time for the painfully slow calculations to come? Or instead play peaceful, low-contact openings like the Réti, hoping to avoid complications? Or maybe revert to "system" openings like the Colle/Semi-Slav or the Stonewall? Are people with particular styles of play less vulnerable to fatigue than others? Maybe the seasoned tournament competitors on the ChessPublishing staff have had to face this problem, too?